var show=document.getElementById("show"),
	is_run=false;

//滚动监听
window.addEventListener("scroll",function(){	
	if(!is_run){
		body_h=document.documentElement.scrollTop+document.body.scrollTop;
		if(body_h>220){
			show.style.height='204px';
		}else{
			show.style.height='';
		}
	}
	var hh=document.documentElement.scrollTop+document.body.scrollTop;
//!is_run?hh>560?go_top.style.display='block':go_top.style.display='':'';
})